1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus having a printing medium feeding unit for feeding a printing medium.
2. Description of the Related Art
Typical image forming apparatuses such as printers or copy machines include a sheet feeding cassette which stores a printing medium such as a paper or overhead projection film, a printing unit which prints an image onto the printing medium, and a printing medium feeding unit which feeds the printing medium. The printing medium feeding unit is disposed at a position in the printing unit where the printing medium is loaded in and out.
FIG. 1 is a perspective view of a conventional feeding unit for a printing medium P. The feeding medium includes a feed roller 2 and an idle roller 3 facing each other. The printing medium P is fed as the feed roller 2 and the idle roller 3 rotate. When the printing medium P is jammed during feeding, a cover is opened so that the interior of the main frame of an image forming apparatus is exposed, or a sheet feeding cassette 1 that stores the printing medium P is separated from the main frame to remove the jammed printing medium P. The printing medium P caught between the feed roller 2 and the idle roller 3 is pulled to remove the jammed printing medium P. The feed roller 2 and the idle roller 3 are elastically pressed with each other to generate feed force, so a large amount of external force may be needed to pull the printing medium P. At this time, the printing medium P may be crumpled. To prevent the printing medium P from being crumpled, the printing medium P must be pulled carefully and slowly. When the amount of external force to pull the printing medium P exceeds the fracture strength of the printing medium P, the printing medium P may be torn. Further, if excessive force is applied, parts of the apparatus that transfer driving force to the feed roller may be damaged. In addition, it is difficult to remove a torn printing medium P, and the pieces of the torn printing medium P torn may be caught between parts operating in the main frame of the image forming apparatus, so the apparatus may malfunction.
Accordingly, there is a need for an improved printing medium feeding unit which minimizes crumpling and tearing of a printing medium when removing a jammed printing medium.